I am an Ubuntu user with Google Chrome 39.0 and whenever I enter a Google Spreadsheet-document (with Chrome), I get a warning header saying that "This version of Firefox is no longer supported, please upgrade to a supported browser".
What have I done wrong? How come Google thinks I'm using Firefox when I'm using their own browser? I have not enabled emulation in the developer tools.
When checking my user-agent at a 3rd party website, it says "Mozilla/5.0 (Windows NT 6.1; WOW64; rv:15.0) Gecko/20120427 Firefox/15.0a1".